Outbreak of CTX-M-15-Producing Klebsiella pneumoniae in the Intensive Care Unit of a French Hospital Amelie Carre ¨ r, 1 Ludovic Lassel, 1 Nicolas Fortineau, 1 Meriem Mansouri, 1 Nadia Anguel, 2 Christian Richard, 2 and Patrice Nordmann 1 The CTX-M-15 extended spectrum b-lactamase (ESBL)-producing Klebsiella pneumoniae isolates were identified in 36 patients hospitalized from December 2006 to September 2007 in the medical intensive care unit (ICU) of the Bice ˆtre hospital, South Paris, France. The incidence of colonization and=or infection was 4.8%. Eighty-nine percent of the ESBL-producing K. pneumoniae isolates were acquired in the ICU, and only 8.3% of the patients were infected. Pulsed field gel electrophoresis (PFGE) analysis of the isolates showed that 32 isolates were clonally related and contained a 160-kb plasmid carrying the bla CTX-M-15 , bla OXA-1 , bla TEM-1 , and aac6 0 -Ib-cr genes. CTX-M-15-producing Escherichia coli isolates collected in the ward during the same period of time contained distinct plasmids and were not clonally related. This study highlights the possible occurrence of outbreaks due to CTX-M-producing K. pneumoniae within hospital settings, whereas CTX-Ms are mostly reported in E. coli in community-acquired infections. Introduction T EM- and SHV-type extended spectrum b-lactamase (ESBL)-producing Klebsiella pneumoniae were extensively reported as a source of nosocomial outbreaks mostly in the intensive care units (ICUs) in the 1990s. 4 However, due to implementation of control measures and close monitoring of ESBL dissemination, their prevalence has decreased signifi- cantly. 19 Since the third millennium, non-TEM, non-SHV ESBLs of the CTX-M type have emerged worldwide. They are now the main ESBLs found mostly in Escherichia coli reported as a source of community-acquired and urinary tract infections in Europe. 31 Spread of CTX-M types in Enterobacteriaceae and mostly in E. coli was described in particular in the UK, 39 France, 17 Spain, 29 and Portugal. 24 Further, dissemination is reported worldwide in Asia 27 and North and South America. 18,38 The CTX-M-15 b-lactamase is now the most common CTX-M type reported worldwide after it was first identified in enterobacterial isolates from India. 13 The rapid dissemi- nation of the bla CTX-M-15 gene in E. coli is enhanced by its plasmid location and likely by the insertion sequence ISEcp1 that may act as a transposition vehicle. 32 Despite being first recovered from community infections, CTX-M-15-producing E. coli have been involved in nosocomial outbreaks, as re- ported in France. 14 Although CTX-Ms have been identified in many enterobacterial species, outbreaks of CTX-M-producing K. pneumoniae are still rare. We report here a major nosocomial outbreak of CTX-M-15-producing K. pneumoniae in France. This study underlines that novel bla CTX-M genes may begin to spread in hospital settings in K. pneumoniae, a bacterial species frequently identified as a source of ESBL-related nosocomial infections. Materials and Methods Bacteriologic surveillance program Microbiological surveillance at the Bice ˆtre hospital (sub- urb of Paris, France) included collection of rectal swabs at admission and then at weekly intervals since 1992 in ICUs. Specimens were inoculated on a specific chromogenic cef- podoxime-containing medium (chromID TM ESBL; bioMe ´r- ieux, la Balme-les-Grottes, France). 34 Measures for preventing patient-to-patient cross- contamination consisted of isolation measures and use of alcoholic hand rub since 2002. Epidemiological and clinical data Seventy nonduplicated ESBL-producing Enterobacteriaceae isolates were recovered from 64 patients hospitalized in the 16 beds of the ICU of the Bice ˆtre hospital from December 1 Service de Bacte ´riologie-Virologie, Ho ˆ pital de Bice ˆtre, Le Kremlin-Bice ˆtre, France. 2 Medical ICU Ho ˆ pital de Bice ˆtre, Assistance Publique=Ho ˆ pitaux de Paris, Faculte ´ de Me ´decine Paris Sud, K. Bice ˆtre, South Paris, France. MICROBIAL DRUG RESISTANCE Volume 15, Number 1, 2009 ª Mary Ann Liebert, Inc. DOI: 10.1089=mdr.2009.0868 47